Tower cranes are used in myriad environments. Two of the more common environments are construction sites and shipbuilding facilities, because of the combination of height and lifting capacity this type of crane provides. A tower crane typically includes a base, a mast, and a crane jib. The base is fixed to the ground, and is also connected to the mast. A slewing unit is connected to the mast and is used to rotate the crane. The crane jib includes, among other things, a load-bearing section, a counter jib section, and the operator cab.
The load-bearing section of the crane jib typically carries a load. The counter jib section is connected to the load-bearing section, and carries a counterweight to balance the crane jib while the load-bearing section is carrying a load. The operator cab is usually located near the top of the mast, and may be attached to the crane jib. However, other tower cranes may have the operator cab mounted partway down the mast. No matter its specific location, a crane operator sits in the operator cab and controls the crane. In some instances, a crane operator can remotely control one or more tower cranes from the ground.
In some environments, a plurality of tower cranes may be operated in relatively close proximity. Thus, while it is unlikely, it has been postulated that the crane jibs of two or more tower cranes could collide. Hence, there is a need for a collision avoidance/warning system that is able to determine the three-dimensional (3D) angular orientation (e.g., attitude and heading angle) of a crane's own crane jib and of other crane jibs working at a particular site. There is also a need for a method to compute calibration parameters associated with magnetometer measurements in the tower crane operating environment, and to initialize/align the filters implemented in the system. The present invention addresses at least this need.